As is known, winding machines divide wire material coming from a feed bobbin, which is generally large-sized, onto smaller bobbins, which are then used in subsequent manufacturing processes. In the pay-off unit, the wire is unwound from the feed bobbin by passing it over a snub pulley. The pulley is generally stationary and positioned centrally with respect to the feed bobbin. Thus, while unwinding, the wire moves laterally, forming a variable angle with the pulley. In some cases, and especially for high-speed work with multiple-end wire (formed from a plurality of single wires wound together), this situation can lead to undesired crossing, overlapping and twisting, possibly resulting in breaks.
The known solution for overcoming this problem is to mount the pulley so that it can freely slide along an axis parallel to the feed bobbin. The pulley is pulled by the wire and follows the movement of the wire itself. This solution is not however entirely satisfactory, since the friction resulting from the dragging of the pulley can lead to malfunctions and breakage of the wire. It is therefore necessary to ensure a careful take-up of the wire material (often multiple strand) onto the bobbins in order to prevent kinking, winding defects, etc., which could negatively influence the subsequent manufacturing processes.
Known winding units provide take-up devices in which a strand of the wire is grasped by a gripper positioned at one end of the bobbin to be filled. Once the end of the wire is grasped, the rotation of the bobbin causes the wire to wind onto that same bobbin. However, this creates the so-called “bridge effect” problem: the section of wire extending between the gripper and the initial turns wound on the bobbin quill sticks out from the quill, as it is under tension by the flange of the bobbin. Consequently, some turns are wound onto the raised section of wire instead of directly onto the bobbin's quill, causing a bulge in the winding that can cause problems in subsequent manufacturing processes. Machines of the prior art do not offer a satisfactory solution to this problem.